Rubidium superoxide: a p-electron Mott insulator

Abstract

Rubidium superoxide, RbO_2, is a rare example of a solid with partially-filled electronic p states, which allows to study the interplay of spin and orbital order and other effects of strong electronic correlations in a material that is quite different from the conventional d or f electron systems. Here we show, using a combination of density functional theory (DFT) and dynamical mean-field theory, that at room temperature RbO_2 is indeed a paramagnetic Mott insulator. We construct the metal-insulator phase diagram as a function of temperature and Hubbard interaction parameters U and J. Due to the strong particle-hole asymmetry of the RbO_2 band-structure, we find strong differences compared to a simple semi-elliptical density of states, which is often used to study the multiband Hubbard model. In agreement with our previous DFT study, we also find indications for complex spin and orbital order at low temperatures.

6 pages, 8 figures

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• Detecting phase transitions and crossovers in Hubbard models using the fidelity susceptibility
• Novel chemistry of lithium oxides and superconducting low-pressure LiO4
• Single-site DFT+DMFT for vanadium dioxide using bond-centered orbitals
• Correlated Electronic Structures and the Phase Diagram of Hydrocarbon-based Superconductors
• Origin of monoclinic distortion and its impact on the electronic properties in KO${}_2$
• Spin-gap formation due to spin-Peierls instability in $\pi$-orbital-ordered NaO${}_2$
• Spin-Orbital Ordering in Alkali Superoxides